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Several pod characteristics were evaluated to select methods for determining optimum maturity for mechanical harvest of flat podded `Roma II' beans (Phaseolus vulgaris L.). The test was conducted over a 3-year period (1993-1995) at Crossville, Tenn. A total length of 3.6 to 4.4 inches (90 to 112 mm) for the center seed from each of 10 of the more mature pods was a rather reliable and rapid field guide for determining optimum maturity for mechanical harvest of `Roma II' bush beans.
Eleven filet snap bean cultivars (Phaseolus vulgaris L.) were evaluated near Crossville, Tenn., in 1995 and 1996. `Minuette' and `Pluto' were among the most productive cultivars in 1995, while `Carlo', `Masai', and `Minuette' were among the most productive cultivars in 1996. In 1995, `Maxibel' produced the greatest percentage of pods No. 3 or larger in sieve size while in 1996, `Carlo', `Dandy', `Maxibel', and `Teseo' were among cultivars that produced the highest percentage of pods No. 3 or larger sieve size. `Flevoro', `Nickel', and `Pluto' pods were firmer than pods of all cultivars except `Axel', `Masai', and `Maxibel' in 1995. In 1996, pods of `Flevoro' were firmer than pods of all cultivars except `Carlo', `Maxibel' and `Nickel'. Pods of `Minuette', and `Rapier' were darker in color than pods of all cultivars except `Axel' and `Teseo'. `Maxibel' produced the longest pods, while `Axel' produced shorter pods than all cultivars except `Masai' and `Rapier'. `Masai' in 1995, and `Masai' and `Nickel' in 1996 produced the smoothest pods. `Dandy' and `Maxibel' pods had the most curvature in 1995, while in 1996, `Maxibel' had more pod curvature than all cultivars except `Carlo', `andy', `Nickel', and `Teseo'.
Light distribution in two cultivars on three dwarfing rootstocks in three high-density apple tree training systems was measured in the sixth leaf beginning at full bloom and continuing through the season. Training system had a significant effect on light penetration into the lowest point of the canopy (measured at 0.5 m), with the slender spindle being significantly darker than either the central leader or the vertical axis, although all three systems were below the threshold value of 30% full sun (FS) needed to maintain productivity for most of the season. Cultivar had no significant effect; however, trees of both `Jonagold' and `Empire' fell below 20% FS early in the season and remained there until late in the season. Rootstock had the greatest effect, with trees on M9 and M26 being significantly darker in the lower canopy than trees on Mark. Trees on M26 and M9 fell below 10% FS early in the season and remained there, while trees on Mark never fell below 20% FS.
Abstract
The effects of repetitive subculturing, cytokinin species and concentration, basal medium, and gelatinizing constituent were studied to maximize shoot multiplication of Hydrangea macrophylla Thunb. ‘Rose Supreme’ shoot tip cultures. Cytokinin treatments of BA or 2iP at 2, 4, 8, 16, or 32 μm were incorporated into woody plant medium (WPM) solidified with 6 g·liter−1 Sigma agar. Cultures grown on 8 μm BA produced the greatest number of useable shoots per 4-week subculture. No treatment stimulated shoot multiplication until the 2nd subculture, after which shoot multiplication remained constant within treatments through the 5th subculture. Results indicate no difference in number of shoots produced per subculture on modified Gamborg's B5, modified Murashige and Skoog basal medium, or WPM when incorporating 8 μm BA and 6 g·liter−1 Sigma agar. No difference in shoot multiplication was observed between 6 g·liter−1 Sigma agar and 2 g·liter−1 Gel-Rite when incorporated into WPM containing 8 μm BA. However, culture fresh weight and shoot length was greater for cultures on Gel-Rite than for cultures on agar. Chemical names used: N-(phenylmethyl)-lH-purin-6-amine (BA) and N-(3-methyl-2-butenyl)-lH-purin-6-amine (2iP).
Abstract
Conventional tillage (CT), no-tillage (NT), and rotary strip-tillage (RT) methods were combined with row spacings of 0.46 m (28 plants/m2) and 0.92 m (56 plants/m2) in 1985 and 1986 snap bean (Phaseolus vulgaris L.) tests with a split-plot factorial arrangement of treatments. Yields were lowest with NT and 0.92-m row spacings both years, while plant stands were lowest with NT and RT. Plant lodging was lowest with NT and highest with CT each year. Pod clustering and broken pods following machine harvest were lowest with NT both years, while rotten pods and percentage no. 2 to 4 sieve-size pods were lowest with NT in 1986. Incidence of broken pods was higher with the 0.46-m row spacing than with the 0.92-m row spacing in 1985 and the incidence of rotten pods was greatest with the 0.46-m row spacing in 1986. The 0.46-m row spacing improved yields over the 0.92-m spacing, with minimal difference in pod quality. Weed control was less effective with NT than with CT and RT methods.
This paper details the development and verification of ROSESIM, a computer simulation model of the growth of `Royalty' roses (Rosa hybrida L.) based on experimentally observed growth responses from pinch until flowering under 15 combinations of constant photosynthetic photon flux (PPF), day temperature (DT), and night temperature (NT). Selected according to a rotatable central composite design, these treatment combinations represent commercial greenhouse conditions during the winter and spring in the midwestern United States; each selected condition was maintained in an environmental growth chamber having 12-hour photoperiods. ROSESIM incorporates regression models of four flower development characteristics (days from pinch to visible bud, first color, sepal reflex, and flowering) that are full quadratic polynomials in PPF, DT, and NT. ROSESIM also incorporates mathematical models of nine plant growth characteristics (stem length and the following fresh and dry weights: stem, leaf, flower, and total) based on data recorded every 10 days and at flowering. At each design point, a cubic regression in time (days from pinch) estimated the plant growth characteristics on intermediate days; then difference equations were developed to predict the resulting daily growth increments as third-degree polynomial functions of days from pinch, PPF, DT, and NT. ROSESIM was verified by plotting against time each simulated plant growth characteristic and the associated experimental observations for the eight factorial design points defining the region of interest. Moreover, one-way analysis of variance procedures were applied to the differences between ROSESIM predictions and the corresponding observed means for all 15 treatment combinations. At 20 days from pinch, significant differences (P < 0.05) were observed for all nine plant growth characteristics. At 30 and 40 days from pinch, only flower fresh and dry weights yielded significant differences; at flowering, none of the 13 selected responses yielded significant differences. These graphical and statistical comparisons provide good evidence of ROSESIM's ability to predict the growth response of `Royalty' roses over a wide range of constant environmental conditions.
No-till (NT) culture has worked well with many agronomic crops; however, NT culture has been less successful with vegetable crops. `Mountain Pride' tomatoes were grown under (NT) and conventional-till (CT) culture at the Plateau Experiment Station. During the first two years of the study, both NT and CT plots were tilled in the fall and sowed in a winter wheat cover crop. In the third year of the study, a continuous NT culture was maintained. Tomato yields were identical from the two tillage practices in the first year. In the second year, yields were significantly higher from NT tomatoes than CT tomatoes. The trend reversed in the third year with CT producing significantly more yield than NT culture. In addition, NT tomato plants were stunted and roots were observed to grow laterally near the soil surface. Production of NT tomatoes following a winter wheat cover crop appears feasible; however, continuous NT was not promising.
Six processing type sweet corn cultivars were evaluated for productivity and production problems at eight planting dates at the Plateau Experiment Station at Crossville, TN. Plant size and yields declined rapidly after the fourth planting date. During this period soil moisture was adequate and temperatures were relatively cool, therefore, plant growth responses may have been attributed to day length or light interception. Insect populations and insect damage increased as the harvest season progressed. `Reveille' had poor ear fill throughout the season, while percentage ear fill of all of the other cultivars, with the exception of `More', decreased rapidly after the fourth planting date. `More' plants were the most vigorous throughout the trial. `More' was one of the most productive cultivars throughout the season and especially at the later planting dates.
A planting of sawdust-mulched highbush blueberries (cv. Bluecrop) was established on a Captina silt loam at the Univ. of Arkansas Research and Extension Center, Fayetteville, in 1994. Nitrogen rate and method of delivery treatments were begun that year and continued through the first two fruiting years (1996 and 1997). Rates included 0, 67, 134, 201, and 268 kg·ha-1 N using ammonium sulfate during the fruiting years (one-half and two-thirds these rates in 1994 and 1995, respectively), and methods of delivery included dry, surface-applied, and fertigation. Total N for the year was applied in three applications for the dry application and in 12 applications using fertigation. Neither yield nor berry mass were statistically significantly affected by N rate or method of delivery. Also, method of delivery had little effect on foliar levels of any macro- and microelements. Rate of N influenced foliar N most years, with the highest N rate increasing foliar N the greatest. The N rate required to consistently achieve adequate foliar N levels (minimum of 1.6% N) was 134 kg·ha-1. Foliar levels >2.0% were common with the two highest N rates. Foliar Mg and Mn were also influenced by N rate, with the lowest Mg level found for the highest N rate, while excess foliar Mn (800 to 100 ppm) was common with the higher N rates in 1997.